Kentucky's U.S. Senate candidates had a hard time talking about farming without slinging mud.

Republican Sen. Mitch McConnell and Democratic challenger Alison Lundergan Grimes took turns attacking each other in a cramped board room of the Kentucky Farm Bureau on Wednesday in the candidates' first joint question-and-answer session of the contentious campaign.

Grimes set the tone early by attacking McConnell in her opening statement for his prolonged absences from the Senate Agriculture Committee. By not showing up, Grimes said, McConnell diluted his influence, which led to his inability to stop the lapse in the federal farm bill last year that provided crop insurance for Kentucky farmers.

"When it comes to the Agriculture Committee, did Sen. McConnell bother to show up?" Grimes said. "No, for nearly three years he has missed every Agriculture Committee meeting."

The McConnell campaign noted after the forum that crop insurance was not affected by the lapse, citing a report from the Congressional Research Service.

And McConnell, the Senate's top-ranking Republican, quickly shot back at the forum that the farm bill he eventually helped pass was a good deal but "it's probably not as good a deal as a $400 a day tour bus," a reference to the campaign bus Grimes rented from her father's company that the McConnell campaign has said could be a potential illegal campaign gift.

McConnell also tried to blunt the criticism for missing committee meetings. He told reporters afterward: "I think she doesn't really understand the legislative process. If you're the leader of one of the parties, you have more consequential things to do than simply go to hearings." He added he would not resign from his committees because he wants to preserve his vote.

Grimes, meanwhile, tried to defuse the flap over her campaign's bus rental, saying it was the result of "baseless, bullying accusations" from McConnell's camp.

During their face-to-face encounter, McConnell criticized Grimes for not giving a straight answer to a question about international trade agreements, pointing out that Grimes' Democratic mentors and supporters oppose such agreements that would benefit Kentucky farmers.

"You just heard him think that I somehow didn't directly answer (the) question. Senator, I do speak for myself. Women aren't supposed to just be seen, we will be heard," Grimes said before saying she supports free and fair trade agreements.

Agriculture leaders from across Kentucky asked about immigration reform for migrant workers, water supply for drying farmlands and a tax deduction that benefits farmers who purchase heavy equipment.

But despite the pointed questions, the candidates' answers routinely found their way back to the same themes: McConnell saying a vote for Grimes would be a vote for President Barack Obama's policies and Grimes saying McConnell's 30 years in the Senate have done nothing for Kentucky.

"We do these in every race and really and truly this one was pretty mild from what we sometimes expect and hear out there," Farm Bureau President Mark Haney said. "I thought both campaigns came in well-versed on agriculture issues. They understood the questions that we asked and gave us the opportunity to explain our policy and then fielded the question from a very appropriate angle."

The candidates did disagree on some tax issues, with McConnell saying an expired tax deduction on heavy farm equipment would likely be extended for another two years. But Grimes called for the Senate to make the deduction permanent to "give our farmers cash flow to do their family business."

On immigration, Grimes blamed McConnell's opposition to last year's bipartisan Senate immigration bill as the cause for the "crisis at the border today" with the influx of children placing a burden on the United State immigration enforcement.

"He said 'no' to thousands of troops securing our borders. He said 'no' to making sure we could have an earned pathway to citizenship," she said.

McConnell said he supports legal immigration but not comprehensive immigration reform, adding that "sometimes we don't do comprehensive well," pointing to the voluminous federal health care law as an example.

"What is holding back immigration right now is American people's legitimate concern the federal government is simply unwilling to secure the borders. And so it ruins the environment for improving legal immigration," McConnell said. "I support legal immigration. We need to make some changes in it. It needs to be more merit based, we need to tilt it toward people who can immediately be productive in our country and make a difference."

Wednesday's forum was a warmup for the statewide televised debate on Oct. 13.

Kentucky's U.S. Senate candidates had a hard time talking about farming without slinging mud.Republican Sen. Mitch McConnell and Democratic challenger Alison Lundergan Grimes took turns attacking each other in a cramped board room of the Kentucky Farm Bureau on Wednesday in...